/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.neo4j.internal.counts;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Changes to counts, kept as {@link AtomicLong} to allow for concurrent threads incrementing/decrementing.
 * As part of checkpoint a new instance is created and the old (now immutable) instance accessible to read from while those counts are written to
 * the backing tree.
 */
class MapCountsChanges extends CountsChanges {
    MapCountsChanges() {
        super(new ConcurrentHashMap<>());
    }

    @Override
    protected CountsChanges fork() {
        return new MapCountsChanges();
    }
}
